Multistage air cleaner including pulse cleaning system

ABSTRACT

A V-pack filter includes a frame construction having a first frame structure and a second frame structure. The V-pack filter also includes first and second panel sections mounted in extension between the first and second frame structures. The first panel section has first and second ends. The second panel section has third and fourth ends. The first and third ends have a first distance therebetween while the second and fourth ends have a second distance therebetween. The second distance is generally greater than the first distance. The first and second panel sections and the second frame structure define an air flow aperture. A seal arrangement circumscribes the air flow aperture and projects outwardly from the second frame structure. The first frame structure defines a first receiver indent. Assemblies and methods are also included.

This application is a continuation of application Ser. No. 11/092,513,filed Mar. 29, 2005; application Ser. No. 11/092,513 is a continuationof application Ser. No. 10/756,578, filed Jan. 12, 2004, issued as U.S.Pat. No. 6,872,237; application Ser. No. 10/756,578 is a divisional ofapplication Ser. No. 09/980,270, filed Apr. 12, 2002, issued as U.S.Pat. No. 6,676,721; application Ser. No. 09/980,270 is a national stageapplication filed under 35 U.S.C. § 371 of International ApplicationPCT/US00/15436, filed Jun. 2, 2000; International ApplicationPCT/US00/15436 claims priority to U.S. application Ser. No. 09/452,311,filed Dec. 1, 1999 and U.S. application Ser. No. 09/325,697, filed Jun.3, 1999. Each of application Ser. Nos. 11/092,513, 10/756,578,09/980,270; PCT/US00/15436; 09/452,311; and 09/325,697 is incorporatedby reference herein

FIELD OF THE INVENTION

The present disclosure relates to air cleaners and particularly concernsair cleaners for cleaning combustion air directed to the engine airintake of large vehicles and equipment. The disclosure concernspreferred designs of air cleaners for such use, and methods of assemblyand use.

BACKGROUND OF THE INVENTION

In general, combustion air for engines needs to be filtered to preventparticulates, otherwise carried in the intake air stream, from reachingsensitive engine components. As a result, nearly every engine systeminvolving combustion air includes an air cleaner assembly of some typepositioned in the intake air stream.

Many air cleaner assemblies generally comprise a housing through whichthe air is directed during filtration or cleaning. In some systems, aremovable and replaceable filter element, or a combination of suchfilter elements, is provided within the housing. In use, the air isdirected through the filter element(s) as it moves through the housing.In time, the filter element(s) becomes occluded or loaded with aconcomitant increase in restriction across the air cleaner. At anappropriate service point, the filter element(s) is removed and iseither refurbished (cleaned) or replaced.

Certain very large and powerful equipment types generate unique problemswith respect to air cleaner operation. Consider large earth movers, haultrucks, and other very large types of construction and mining equipmentthat have 500-2,000 horsepower (hp) (37.3-149.2 KW) engines.

Such equipment operates for extended periods in extremely dustyenvironments. Such equipment also has very large volume demands forcombustion air. This means very large amounts of particle-laden air onan almost continuous basis is passing through the air cleaner system.Indeed, the typical environments of use, for example construction sitesand mining sites, are sites characterized by relatively large amounts ofair borne particulates of a variety of sizes and populationdistribution. Special heavy-duty multistage filtration units have beendesigned for use with such equipment. One such design has been availablefrom Donaldson Company, Inc. of Minneapolis, Minn. under the designationSRG Donaclone™. Such products are designed for an air flow of up toapproximately 1,300-4,500 cubic feet per minute (cfm) (81,000-281,000pounds water per minute (pwm)) and are available in single or dual unitdesigns. In general, such arrangements are multistaged. In a firststage, a precleaner is provided for removal of up to 95% of the dirt inthe air stream before it reaches the filters. Such precleaners generallyoperate by directing the inlet air flow through a plurality of cyclonictubes with dust separation occurring as a result of the cyclonic airflow. Cyclonic precleaners are described, for example, in U.S. Pat. No.5,693,109, incorporated herein by reference.

In the second stage, the air from the precleaner is directed into andthrough an air filter system, typically a filter system provided by twoelements: an outer primary filter element and an internal secondary orsafety element. The housings are generally configured so that,periodically, the primary filter (and if desired the secondary filter)can be removed and be refurbished or replaced.

SUMMARY

I. Summary of U.S. patent application Ser. No. 09/325,697

In one aspect of U.S. patent application Ser. No. 09/325,697, an exampleembodiment involves a filter assembly. The filter assembly includes ahousing that defines first and second chambers, a first stage aircleaner, a second stage air cleaner, and a pulse jet cleaningarrangement. The first stage air cleaner is positioned in the firstchamber and includes a first filter element through which air to befiltered is directed during use. The second stage air cleaner ispositioned in the second chamber and includes at least one removable andreplaceable filter element through which air is directed during use. Thepulse jet cleaning arrangement is constructed and arranged toselectively direct a pulse jet of air, in a reverse direction, throughsaid first filter element.

In another aspect of U.S. Ser. No. 09/325,697, an apparatus includes afirst V-pack filter and a lift mechanism. The first V-pack filter has afirst, lower end and a second, upper end. The second, upper end includesan air flow exit aperture; a first seal arrangement, or gasket,circumscribing the air flow exit aperture and projecting outwardly fromsaid second, upper end; and a hard stop arrangement projecting outwardlyfrom said second, upper end. The lift mechanism includes a basestructure, a movable seat secured to the base structure, and a pivotallymounted control arm. The movable seat has a first, raised orientationand a second, lowered orientation. The pivotally mounted control armraises the movable seat to the first raised orientation and lowers themovable seat to the second, lowered orientation. The first V-pack filterand the lift mechanism are constructed and arranged such that when thelift mechanism is positioned in the first, raised orientation, the firstV-pack filter is pressed against a portion of a housing in a lockedposition with the first seal arrangement pressed to form a seal and thehard stop limiting an extent of movement of the V-pack toward thehousing. When the lift mechanism is in the second, lowered orientation,the first V-pack filter is released from the locked position.

In another aspect of U.S. Ser. No. 09/325,697, a method of operating anengine air intake filter assembly is discussed. The filter assemblyincludes a first chamber to house a first stage air cleaner, a secondchamber to house a second stage air cleaner, and a pulse jet cleaningarrangement constructed and arranged to selectively direct pulses of airthrough the first stage air cleaner. The method includes measuring apressure drop across the first stage air cleaner during engineoperation; measuring an engine load during the engine operation; andactivating a pulse valve of the pulse jet cleaning arrangement to directa pulse of air, in a reverse direction, through the first stage aircleaner in response to the engine load being below a predeterminedengine load and the pressure drop exceeding a predetermined pressuredrop.

II. Summary of the Interlocking Arrangement

In one aspect of this discussion, an example embodiment involves anapparatus. The apparatus includes a retention mechanism, a V-packfilter, and an interlocking arrangement. The retention mechanismincludes a base structure and a movable seat. The movable seat issecured to the base structure and has a first, locked orientation and asecond, unlocked orientation. The V-pack filter includes a frameconstruction having first and second frame structures. The V-pack filteralso includes first and second panel sections mounted in extensionbetween the first and second frame structures. The first panel sectionhas first and second ends. The second panel section has third and fourthends. The first and third ends have a first distance therebetween. Thesecond and fourth ends have a second distance therebetween. The seconddistance is generally greater than the first distance thus causing aV-shape. The first and second panel sections and the second framestructure define an air flow aperture. The V-pack filter also includes asealing arrangement that circumscribes the air flow aperture andprojects outwardly from the second frame structure.

The apparatus has a first, operable orientation wherein the V-packfilter is operably mounted in the apparatus. The apparatus also has asecond, unload orientation wherein the V-pack filter is in a loosenedpositioned for separation from the apparatus. The interlockingarrangement includes first and second interlocking devices. The V-packfilter includes the first interlocking device. The second interlockingdevice is orientated in the apparatus and is mounted on a memberseparate from the V-pack filter. The interlocking arrangement isconstructed and arranged such that when the retention system is in thefirst, locked orientation and the apparatus is oriented in the first,operable orientation, the first and second interlocking devices engage,typically by a male/female fit.

In another aspect of this discussion, an example embodiment involves aV-pack filter. The V-pack filter includes structure analogous to thatabove.

In another aspect of this discussion, an example embodiment involves amethod of locking a V-pack filter in an operable position around anaperture.

III. Summary of the Logic Control System

In one aspect of this discussion, an example embodiment includes amethod of operating an engine air intake filter assembly having a pulsejet cleaning arrangement constructed and arranged to selectively directpulses of air through an air filter arrangement. The method includesmeasuring a pressure drop across the filter arrangement; measuring anengine load during an engine operation; and activating a pulse valve ofthe pulse jet cleaning arrangement to direct a pulse of air, in areverse direction, through the air filter arrangement in response to theengine load being below a predetermined engine load and the pressuredrop exceeding a predetermined pressure drop.

In another aspect of this discussion, an example embodiment includes asystem for operating an engine air intake filter assembly having a pulsejet cleaning arrangement constructed and arranged to selectively directpulses of air through an air filter arrangement. The system includes apressure drop component, an engine load component, and a pulse firingcomponent. The pressure drop component receives a measured pressure dropacross the air filter arrangement. The engine load component receives ameasured engine load during an engine operation. The pulse firingcomponent activates a pulse valve of the pulse jet cleaning arrangementto direct a pulse of air, in a reverse direction, through the air filterarrangement in response to the engine load being below a predeterminedengine load and the pressure drop exceeding a predetermined pressuredrop.

Another aspect of this discussion includes a computer program productreadable by a computing system and encoding instructions for a computerprocess for operating an engine air intake filter assembly having apulse jet cleaning arrangement constructed and arranged to selectivelydirect pulses of air through an air filter arrangement. The computerprocess includes the method as previously discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front elevational view of an assembly according tothe present invention;

FIG. 2 is a schematic, right side elevational view of the assembly shownin FIG. 1;

FIG. 3 is a schematic, top plan view of the assembly shown in FIG. 1;

FIG. 4 is a schematic, front perspective view of the assembly shown inFIG. 1;

FIG. 5 is a schematic, rear perspective view of the assembly shown inFIG. 1;

FIG. 6 is a schematic, front perspective view analogous to FIG. 4, withportions broken away to show internal detail;

FIG. 7 is a schematic, front elevational view of the assembly asdepicted in FIG. 6;

FIG. 8 is a schematic, internal prospective view of portions of theassembly of FIG. 1;

FIG. 9 is a schematic, front elevational view of the assembly asdepicted in FIG. 8;

FIG. 10 is a schematic, enlarged, front elevational view of portions ofthe internal assembly of FIG. 1;

FIG. 11 is a schematic, enlarged, side elevational view of portions ofthe internal assembly of FIG. 1;

FIG. 12 is a schematic, top plan view of the bottom portion of theassembly shown in FIG. 10;

FIG. 13 is a schematic, top perspective view of the bottom portion ofthe assembly shown in FIG. 12;

FIG. 14 is a schematic, side elevational view of the bottom portion ofthe assembly shown in FIG. 12;

FIG. 15 is a schematic, front elevational view of the assembly of FIG. 1with portions of the assembly removed;

FIG. 16 is a schematic, perspective view of the first chamber of theassembly of FIG. 1, with portions broken away to show internal detail;

FIG. 17 is a schematic, perspective view of the primary element of thesecond chamber of the assembly of FIG. 6;

FIG. 18 is a schematic, perspective view of the safety element of thesecond chamber of the assembly of FIG. 6;

FIG. 19 is a schematic, end elevational view of one of the V-packs ofFIG. 6;

FIG. 20 is a schematic, side elevational view of one of the V-packs ofFIG. 6;

FIG. 21 is a schematic, top plan view of one of the V-packs of FIG. 6;

FIG. 22 is a schematic, perspective view of a retention system of theassembly of FIG. 6;

FIG. 23 is a schematic, top plan view of the retention system of FIG.22;

FIG. 24 is a schematic, side elevational view of the retention system ofFIG. 22;

FIG. 25 is a schematic, front elevational view of the retention systemof FIG. 22;

FIG. 26 is a schematic, end elevational view of portions of the secondchamber of the assembly of FIG. 6;

FIG. 27 is a schematic, cross-sectional view taken along line 27-27 ofFIG. 26;

FIG. 28 is a schematic, perspective view of an example embodiment of thecharge tank of the assembly of FIG. 10;

FIG. 29 is a schematic, top plan view of the charge tank of FIG. 28;

FIG. 30 is a schematic, cross-sectional view of the charge tank of FIG.29, taken along line 30-30;

FIG. 31 is a schematic, cross-sectional view of the charge tank of FIG.29, taken along line 31-31;

FIG. 32 is an electrical schematic depicting the interface between acontrol system of the assembly of FIG. 6 and a vehicle;

FIG. 33 is an electrical schematic showing more detail of the controlsystem of FIG. 32;

FIG. 34 is a flow chart of the logic of the control system of FIG. 32;

FIG. 35 is a flow chart depicting more detail of the firing of a pulsevalve by the control system of FIG. 34;

FIG. 36 is a perspective view of a second embodiment of a V-pack filter;

FIG. 37 is a side, elevational view of the V-pack filter of FIG. 36;

FIG. 38 is a top, plan view of the V-pack filter of FIG. 36;

FIG. 39 is cross-sectional view of a second embodiment of a firstchamber of a filter assembly;

FIG. 40 is bottom, plan view of the V-pack filter of FIG. 36;

FIG. 41 is a perspective view of a third embodiment of a V-pack filter;

FIG. 42 is a perspective view of a fourth embodiment of a V-pack filter;and

FIG. 43 is a bottom plan view of a fifth embodiment of a V-pack filter.

DETAILED DESCRIPTION

I. Disclosure of U.S. patent application Ser. No. 09/325,697

A. Environment of Use; System Demand

The arrangements depicted in drawings 1-35 and described in U.S. patentapplication Ser. No. 09/325,697, and the principles defined inassociation with them, were specifically designed for advantageousapplication in certain types of equipment and work environments. Whilethe principles could be applied in a variety of alternate applications,the unique arrangements described are particularly advantageous for theidentified systems of use.

According to U.S. Ser. No. 09/325,697, typical systems in whichequipment of the type defined therein will be useful are engineapplications concerning large engines, typically 500 to 2,000 hp(37.3-149.2 KW). Such engines are generally defined by air flow demandson the order of about 1,300 to 4,500 cfm (81,000 to 281,000 pwm).

According to U.S. Ser. No. 09/325,697, in general, it is desirable thatsuch equipment be able to operate with no more than about 25 inches(63.5 cm) of water restriction across the air cleaner system. Withconventional air filter technology this could mean that, due to airfilter occlusion, the air filters would generally need to be changedwith a frequency of about 250 hours. Longer periods of time between airfilter changing and refurbishment without operation above the limitingrestriction of about 25 inches (63.5 cm) of water have been sought bymanufacturers and users of such equipment.

B. A Typical Improved System According to U.S. Ser. No. 09/325,697

In FIGS. 1-35, an air cleaner system utilizing principles according tothat described in U.S. Ser. No. 09/325,697 is depicted.

Referring to FIG. 1, reference No. 1 generally designates an air cleanerarrangement or assembly utilizing principles according to U.S. Ser. No.09/325,697. As will be apparent from the description of U.S. Ser. No.09/325,697, alternate embodiments, arrangements, and applications aresensible.

In U.S. Ser. No. 09/325,697, the assembly 1, FIG. 1, is depicted infront elevational view. By “front” in this context, reference is meantto a side 3 of the assembly 1 on which one or more access hatches orcovers are provided for normal servicing. For the particular air cleanerassembly 1 depicted in U.S. Ser. No. 09/325,697, mounted on the frontside 3 are first and second access doors, hatches, or covers 5 and 6.The first cover 5 opens to allow service access to a first stage aircleaner assembly; and the second access cover 6 is oriented to allowservice access to a second stage air cleaner assembly.

The first cover 5 is pivotally secured to the assembly 1 by first andsecond hinges 7, 8. Preferably, the first and second hinges 7, 8 areconventional hinges and are typically bolted or riveted to the assembly1 and the first cover 5. The first and second hinges 7, 8 allow thefirst cover 5 to swing outwardly away from the assembly 1 about a fixedaxis A defined by the hinges 7, 8. The first cover 5 also includes alatching device 9. Preferably, the latching device 9 is a conventionallatching device. By the term “conventional,” it is meant any knowndevice that is capable of securing the first cover 5 to the assembly 1.The latching device 9 prevents the first cover 5 from swinging outwardlyaway from the assembly 1.

Although not required for all applications of the technology describedin U.S. Ser. No. 09/325,697, in the particular embodiment shown, theaccess doors or covers 5 and 6 are positioned on the same side, i.e. thefront side 3 of the assembly 1. This will be a particularly convenientdesign for vehicle and equipment manufacturers, since for overallequipment design, the manufacturer need only provide the wide space ofaccess to the air cleaner assembly 1 for removal and servicing ofelements on the front side 3 of the assembly 1.

The particular assembly 1 depicted in FIGS. 1-5 of U.S. Ser. No.09/325,697 is somewhat rectangular in horizontal cross-section. Thus, ithas four sides of which the front side 3 has already been designated.The other sides comprise sides 10, 11, and 12, identified in general inFIG. 1 (front elevation), FIG. 2 (side elevation), and FIG. 3 (topplan). The side 12 would typically be referenced as the back, or rear,side; i.e., the rear side 12 facing opposite the front side 3 of theassembly 1.

Referring to FIG. 4, first and second lifting rings 16, 17 are provided.The first and second lifting rings 16, 17 are attached to first andsecond plates 18, 19, FIG. 7. The first and second plates are secured aspart of the assembly 1 by, for example, welding. The lifting rings 16,17 are arranged and configured to allow a lifting device, such as acrane, to lift the assembly 1 for mounting on a vehicle, such as a heavyhaul truck.

Attention is now directed to FIG. 6, a perspective view of the aircleaner assembly 1, similar to FIG. 4 but with portions broken away toshow internal detail. From reference to FIG. 6, general operation of theoverall air cleaner assembly 1 will be readily understood.

According to U.S. Ser. No. 09/325,697, in general, the air cleanerassembly 1 includes an outer housing 20 divided into first and secondchambers 21 and 22. A first stage air cleaner arrangement 24 ispositioned in chamber 21, and a second stage air cleaner 25 ispositioned in the second chamber 22. For the particular embodimentshown, the chambers 21 and 22 are positioned in a vertical stack withchamber 22 positioned generally above chamber 21 for normal use. In theparticular embodiment illustrated, the first and second chambers 21, 22are manufactured separately from each other and are secured together.

Attention is directed to FIG. 16. FIG. 16 is a schematic, perspectiveview of the first chamber 21 of the assembly 1 (FIG. 6) with portionsbroken away to show internal detail. According to U.S. Ser. No.09/325,697, the first chamber 21 is constructed with first, second,third, and fourth flanges 53-56. Preferably, each of the flanges 53-56includes a plurality of bolt holes 57. Referring back to FIG. 6,analogously, the second chamber 22 is also constructed with first (notshown), second 58, third 59, and fourth (not shown) flanges including aplurality of bolt holes (not shown). The flanges 58, 59 of the secondchamber 22 are arranged and configured to mate with the flanges 53-56(FIG. 16) of the first chamber 21 and the bolt holes 57 of the firstchamber 21 are arranged and configured to align with the bolt holes ofthe second chamber 22, such that a plurality of bolts 50 positionedthrough the plurality of bolt holes 57 secure the first chamber 21 tothe second chamber 22.

According to U.S. Ser. No. 09/325,697, in general, the first or lowerchamber 21, FIGS. 1 and 2, is defined by first, second, third, andfourth side walls 26 (front), 27 (side), 28 (side), and 29 (back).Attention is directed to FIG. 5. Each of the side walls 26-29 (FIGS. 1,2, and 5) has defined therein an open aperture, air inlet, or window 33through which air to be filtered by the air cleaner assembly 1 can passinto the assembly 1 for cleaning. Each of the air inlets 33 is, inpreferred embodiments, covered by a protective screen 34. The air inlet33 and the screen 34 in the rear panel 29 are viewable in FIG. 5, as arethe air inlet 33 and screen 34 in panel 28.

Still referring to FIG. 5 and U.S. Ser. No. 09/325,697, note thatmounted on side wall 28 is a first weather cover 36. Still referring toFIG. 5, note also a second weather cover 37 mounted on or extending fromthe side wall 27. Weather covers, such as first and second weathercovers 36 and 37, protect corresponding air inlets 33 positionedthereunder from entrance by undesirable levels of rain, snow, and thelike.

Referring to FIG. 4, it is noted that the assembly 1 also includes athird weather cover 40 on the front side 3. In the embodiment shown, thethird weather cover 40 is mounted on the first access cover 5. The firstaccess cover 5 includes an air inlet 33 therein, covered by a screen 34.In general these are viewable in FIG. 15.

Referring to FIG. 5 and U.S. Ser. No. 09/325,697, the weather covers 36,37 preferably comprise a single piece of material, such as metal, bentat first and second angles 38, 39, respectively. Preferably, the firstand second angles 38, 39 are approximately ninety degrees. The firstangle 38 separates the first weather cover 36 into first and secondsections 41, 42. Likewise, the second angle 39 separates the secondweather cover 37 into first and second sections 43, 44. In theparticular embodiment depicted, the first sections 41, 43 are attachedas part of the assembly 1. Preferably, the first section 41 of the firstweather cover 36 is attached as part of the assembly 1 by placing thefirst section 41 of the first weather cover 36 under the flanges 54, 58of the first and second chambers 21, 22, respectively, and securing thecover 36 in place by, for example, welding. Likewise, the second section43 of the second weather cover 37 is attached as part of the assembly 1.

Referring to FIG. 4, the first weather cover 36 also includes a thirdsection 47. Preferably, the third section 47 is attached to the firstand second sections 41, 42 of the weather cover 36. For example, thethird section 47 may be welded to the first and second sections 41, 42.Likewise, the second weather cover 37 also includes a third section 46analogous to the third section 47 of the first weather cover 36.

Referring back to FIG. 5, in the preferred embodiment depicted in U.S.Ser. No. 09/325,697, the first sections 41, 43 of the weather covers 36,37, respectively, extend generally perpendicular to the side walls 28,27, respectively, of the assembly 1. The first sections 41, 43 preventundesirable levels of weather elements, such as rain, from entering theair inlets 33 from the top, or parallel directions. In the preferredembodiment of U.S. Ser. No. 09/325,697, the second sections 42, 44 ofthe weather covers 36, 37, respectively, extend generally parallel tothe side walls 28, 27, respectively, or orthogonal to the ground. Thefirst and second sections 42, 44 prevent undesirable levels of weatherelements from entering the air inlets 33 from the side, or perpendiculardirections. Alternatively, the second sections 42, 44 are orientedspaced from, but covering, the air inlets 33 in the walls 28, 27,respectively. Referring back to FIG. 4, the third sections 46, 47prevent the weather elements from entering the air inlets 33 from thefront. Referring back to FIG. 5, the first weather cover 36 is openalong a rear edge 48 and along a bottom edge 49. These are directionsfrom which falling or wind blown elements are less likely to be able toenter the covered air inlet 33 in the side 28 of the assembly 1, andtherefore, these areas are accessible for air to enter the assembly 1.Likewise, the second weather cover 37 is open along a rear edge 51 andalong a bottom edge 52.

It is noted that the assembly 1 does not include, mounted thereon, aweather cover over the air inlet 33 in the rear wall 29. It isanticipated by U.S. Ser. No. 09/325,697 that in typical systems, theassembly 1 will be mounted on the vehicle such that the rear wall 29does not need a weather cover, because the vehicle itself prevents theelements from entering the air inlet 33.

Referring to FIGS. 4 and 5, according to U.S. Ser. No. 09/325,697, theassembly 1 includes a bottom skirt or splash guard 60. The bottom splashguard 60 includes first, second, and third segments 61, 62, and 63mounted to extend outwardly from bottom portions of walls 26, 27, and28, FIG. 1, respectively. The splash guard or skirt 60 inhibitsundesirable levels of water from being splashed up into the air inlet 33from the underside of the assembly 1.

Referring to FIG. 5, the third splash guard section 63, and analogouslythe second section 62, includes a mounting strip 64 by which the splashguard 60 is mounted on the wall 28; a base extension 65; and an angledsplash extension 66. Preferably, the angled splash extension 66 projectsover an angle B, FIG. 5, relative to base section 65 of 110 to 160°,preferably about 1350. Preferably, the base section 65 is mounted on theassembly 1 by a plurality of bolts 69. Of course, other means ofattachment may be used, such as welding.

Referring to FIG. 4, the first or front extension 61 of the splash guard60 includes a mounting strip 67 and a downwardly extending section 68,preferably having an angle C with respect to the mounting strip 67, FIG.2. Preferably the angle C is between 110 to 160°, and most preferably isabout 135°. Preferably, the mounting strip 67 is mounted to the assembly1 by a plurality of bolts 69. Of course, other means of attachment maybe used, such as welding.

It is also noted that the front weather cover 40, FIG. 4, includes adownwardly and rearwardly extending splash guard extension 79 thatextends from a region 96 mounted on surface panel 80 generally towardskirt section 68, preferably at an angle D with respect to region 96,FIG. 2. Preferably, the angle D is between 110 to 160°, and mostpreferably is about 135°. The splash guard extension 79 preventsundesirable levels of water from being splashed up underneath the cover40. The cover 40 also includes a top panel 82 and opposite side panels83, 84 (FIG. 4). It is open, however, underneath edge 85 to allow air toenter the assembly 1.

Referring back to FIG. 5, as indicated in U.S. Ser. No. 09/325,697, airto be filtered by the air cleaner assembly 1 passes into the air cleanerassembly 1 through the air inlets 33. In the preferred embodiment shown,the air inlets 33 allow for direct transfer of the air into the firstchamber 21 (FIG. 6). By the term “direct,” or variants thereof in thiscontext, reference is meant to air flow from the exterior environmentthat does not first pass into the second chamber 22. Referring back toFIG. 6, within the first chamber 21, the air is passed through the firststage air cleaner 24. For the particular arrangement shown in FIG. 6 anddescribed in U.S. Ser. No. 09/325,697, the first stage air cleaner 24includes two V-shaped air filter constructions 94, 95, sometimesreferred to therein as V-packs. Detail concerning the preferredconstruction of the V-shaped filter constructions 94, 95 is provided inU.S. Ser. No. 09/325,697. In general, the V-shaped filter constructions94, 95 are preferably identical in construction, and each includes firstand second opposite filter panels 97 and 98. The panels 97 and 98, foreach V-shaped filter 94, 95, are mounted in a frame 199 to define aninternal, V-shaped, interior chamber or clean air plenum 99. The air isfiltered as it passes from the region exterior to the V-shaped filters94, 95 to the clean air plenum 99. After this filtering in the firststage 24, the air then passes through passageways 100, 101, FIG. 16,into the upper chamber 22.

For the particular arrangement shown in FIG. 6 and described in U.S.Ser. No. 09/325,697, the V-packs or V-shaped air filter constructions94, 95 are vertically oriented. By the term “vertically oriented,” it ismeant that in the normal installation on vehicles or equipment standingon level ground the orientation of the V-shaped filter elements 94, 95will be such that vertices 109, 110, respectively, of the V's aredirected downward. It is, of course, possible to use alternateconstructions in association with the techniques described herein,although the vertically oriented configuration shown in FIG. 6 ispreferred.

Alternate orientations would include an “inverted orientation,” whichwould be one in which the vertices 109, 110 of the V's are directedupward; and, laterally oriented ones, in which the vertices 109, 110 ofthe V's are directed sideways. There would, in general, be two types oflaterally oriented arrangements: one in which the elements 94, 95 arestanding on one of the ends 203, 204; and ones in which the ends 203,204 extend orthogonally to the ground. Of course, alternateconfigurations of the overall assembly 1 would be needed for alternateorientations of the V-packs 94, 95. Although alternate orientations andconfigurations are possible, the “vertical” orientation for the V-shapedfilters 94, 95 will be preferred, for reasons of: air flow, pulsecleaning, assembly, and servicing. The preferred V-packs 94, 95 arecharacterized below in connection with FIGS. 19-21 of U.S. Ser. No.09/325,697.

The upper chamber 22 includes, positioned therein, the second stagefilter system 25. For the arrangement shown, the second stage filtersystem 25 comprises a cylindrical filter construction 123. Attention isdirected to FIGS. 26 and 27. FIG. 26 is a schematic, end elevationalview of portions of the cylindrical filter construction 123. FIG. 27 isa schematic, cross-sectional view taken along line 27-27 of FIG. 26. Forthe particular arrangement shown, the cylindrical construction 123includes a primary element 124, shown in perspective view in FIG. 17,and a secondary or safety element 125, shown in perspective view in FIG.18. During operation, the air is passed through the primary element 124and the safety element 125 into a central clean air plenum 130. Thefiltered air then passes outwardly through outlet tube 131 to the engineair intake duct (not shown).

Periodically, it may be desirable to remove the primary element 124, andin some instances the safety element 125, for inspection and in someinstances refurbishing or replacement. Referring back to FIG. 6 of U.S.Ser. No. 09/325,697, the second cover 6 provides access for this. Thesecond cover 6 is mounted on a cylindrical extension 134 and is securedin place by a clamp arrangement 135. When the clamp arrangement 135,which comprises a strap 136 secured by bolts 137, is loosened, accessthrough the tube or extension 134 is provided to an end 140, FIG. 26, ofthe primary element 124. The primary element 124 can thus be grasped andbe removed from its mounting on the outlet tube 131, FIG. 27, exposingthe safety element 125, FIG. 27, that can also be removed if desired.

Details concerning the preferred construction and mounting of theprimary element 124 and the safety element 125 are provided below and inthe '697 application, in connection with FIGS. 15, 17, 18, 26, and 27.

Attention is directed to FIGS. 7 and 8 of U.S. Ser. No. 09/325,697. FIG.7 is a front elevational view showing the assembly 1 with portions ofthe top, the right side 11, FIG. 1, and the front side 3, FIG. 1,removed to show certain internal parts. In FIG. 8, the assembly 1 isshown without the V-shaped constructions 94, 95, the primary element124, and the safety element 125. FIG. 8 is analogous to FIG. 7, but withadditional portions removed to show more internal detail and representsa perspective view.

Again referring to FIG. 6 and according to U.S. Ser. No. 09/325,697, thefirst stage air cleaner 24 includes a reverse pulse cleaning arrangement154. Periodically, preferably in accord with a selected program scheduleas described hereinbelow, the reverse pulse cleaning system 154 isoperated to direct reverse jets of air through the V-shapedconstructions 94, 95 in the first stage 24. This will serve to knockdust cake off the outer or upstream surfaces of the panels 97 and 98 ofthe V-shaped constructions 94, 95. Referring to FIG. 8, the dislodgeddust will, under gravity influence, pass toward a bottom region 157 ofthe first chamber 21 and outwardly through a dust exhaust valvearrangement 160. A preferred construction of the dust exhaust valvearrangement 160, as shown in FIG. 8, and 12-14, is discussed the '697application.

Referring to FIG. 8 of U.S. Ser. No. 09/325,697, in order to generateand direct the cleaning jets of air, the pulse cleaning system 154includes four pulse jet nozzles 162, 163, 164, 165; two associated witheach V-pack 94, 95 (FIG. 6). Specific preferred constructions of thepulse jet nozzles 162-165 are discussed in greater detail below and inthe '697 application.

Referring to FIGS. 6 and 8 of U.S. Ser. No. 09/325,697, a central baffle170 is positioned in the first chamber 21, between the two V-packs 94,95. The central baffle 170 depends downwardly from a tube sheet 171,generally at least 50% or more, preferably at least 70%, and mostpreferably at least 90% of the distance between a top 180 of the firstchamber 21, and a lowest level 181 of extension of the V-packs 94, 95,when the V-packs 94, 95 are positioned for filtering. Preferably, thebaffle 170 extends below this lower level 181. The baffle 170 helpsprevent dust that has been blown off the V-packs 94, 95 by the air fromthe pulse jet nozzles 162-165 from being transferred to the nextadjacent V-pack 94, 95. Rather, due to the baffle 170, the dust is morelikely to pass downwardly to the bottom 183 of the first chamber 21.

The term “bottom end 183,” when used in connection with thecharacterization of the first chamber 21, refers to a region 184. Itwill be understood from further descriptions that the region 184 is thelocation at which equipment that supports the V-packs 94, 95 ispositioned within the assembly 1. The portion of the housing 20 thatincludes the dust exhaust valve arrangement 160 generally dependsdownwardly from the bottom end 183.

C. The V-Pack Filters of U.S. Ser. No. 09/325,697

Attention is directed to FIGS. 19-21 of U.S. Ser. No. 09/325,697. InFIG. 19, one of the V-packs 94, 95 is depicted. Each V-pack 94, 95comprises a pair of panels 97, 98. The panels 97, 98 each comprise anouter frame 199 with media 200 positioned therein. For the preferredarrangements of U.S. Ser. No. 09/325,697, the media 200 is pleated andoriented such that when the V-pack 94, 95 is positioned in the verticalorientation of FIG. 6, the pleats 201 extend horizontally. In general,the media 200 is potted within the frame 199 by an adhesive materialsuch as PVC plastisol (i.e., a polyvinylchloride). Commerciallyavailable potting plastisols can be used.

According to U.S. Ser. No. 09/325,697, a variety of materials can beutilized for the media 200. In general, what is required is anappropriate media to achieve a preferred level of efficiency for theV-packs 94, 95. The media chosen for the V-packs 94, 95 is a matter ofchoice; a variety of conventional medias can be used. For a high-levelof cleaning from pulse cycles, a robust media is preferred to helpprevent particles from penetrating into the fibers of the media whenloading. That is, it is preferred that the media be of a type such thatparticles will be captured on the outer surface of the media. Usablematerials include cellulose or synthetic fiber media.

On the upstream side, a deposit or layer of polymeric fiber material, or“fine fiber,” generally having a fiber diameter of 5 microns or less,can be used, in some applications. The amount of fine fiber deposited isa matter of design choice for a given application. In general, the morefine fiber that is used, the larger the restriction. Conversely, theless fine fiber that is used, the higher the occurrence of penetrationof the particles during loading. That is, the fine fiber facilitatessurface loading and pulse jet cleaning.

One media comprising a fine fiber deposited onto a paper or cellulosematerial is practiced by Donaldson Company, Inc., the assignee of thepresent application, in products generally identified under thetrademark EON™. These media are manufactured by a trade secret processof Donaldson's. Such media would be useable in arrangements according tothe present invention. However, the technique of fine fiber applicationis not critical to the principles disclosed, and a variety ofconventional, well-known, processes could be used.

According to U.S. Ser. No. 09/325,697, each of the V-packs 94, 95includes first and second opposite end panels 203, 204. The end panels203, 204 close ends of the clean air plenum 99 when the V-packs 94, 95are sealed for use. For convenience, one of the panels 203 is shownhaving a wire handle 209 positioned thereon, FIG. 19. The wire handle209 is secured in extension between brackets 210, 211. The wire handle209 comprises an extension of wire 212 having end stops 213, 214thereon. When a central portion 215 of the flexible wire 212 is pulled,the handle 209 will bow outwardly until the end stops 213, 214 engagethe brackets 210, 211. A flexible, collapsible, handle construction 209is convenient for mounting and dismounting the V-packs 94, 95 and alsofor carrying the V-packs 94, 95.

Of course, alternate handle designs may be used. For example, apivotally mounted rigid handle may in some instances be substituted forthe type of handle configuration depicted in the figures. In general,preferred handle constructions will be ones that have a flat, enclosedconfiguration that can be readily opened to be grasped.

Again according to U.S. Ser. No. 09/325,697, in each V-pack 94, 95, thepair of panels 97, 98 is oriented in a V-shape, as shown in FIG. 19.Along one longitudinal edge 220, 221 of each panel 97, 98, the panels97, 98 are oriented either adjacent one another or closely spaced,whereas along opposite side edges 222, 223, the panels of 97, 98 arespread apart from one another. That is, preferably the panels 97, 98form a V-shape, most preferably having a filter angle E, FIG. 19,between the panels 97, 98, of at least about 5°, preferably within therange of 10 to 25°, most preferably about 13 to 17°.

Referring to FIG. 21 of U.S. Ser. No. 09/325,697, each V-pack 94, 95preferably includes a central spacer 228 separating the V-pack 94, 95into separate regions 229, 230. In use, a separate one of the nozzles162-165, FIG. 8, is directed into each region 229, 230. The centralspacer 228 directs the air from each nozzle 162-165 to an associatedregion 229, 230 of the V-pack filters 94, 95 to provide directed airsufficient to clean the exterior portions of the panels 97, 98.

The air flow exit end 231 of each V-pack 94, 95 includes a sealarrangement, i.e. a gasket, 240 thereon having a first projectionthickness T1. When each V-pack 94, 95 is operatively positioned withinthe air cleaner assembly 1, the seal arrangement 240 is pressed betweenan end 231 of the V-pack 94, 95 and the tube sheet 250, as shown in FIG.7. In general, the seal arrangement 240 is sized to be sealinglypositioned around the aperture 100 in the tube sheet 250, FIG. 7.

The preferred V-packs 94, 95 of U.S. Ser. No. 09/325,697 also include ahard stop arrangement 260 thereon have a second projection thickness T2less than the first thickness T1. Preferably the hard stop arrangement260 is configured to extend the second thickness T2 of at least about0.1 inches (2.5 mm), typically about 0.2 inches (5.1 mm) to 0.3 inches(7.6 mm), above (or outwardly from) a top surface 265 of the V-packframe 199. Also, preferably the seal arrangement 240 is selected suchthat, prior to being pressed, the seal arrangement 240 extends at leastabout 0.1 inches (2.5 mm) to 0.3 inches (7.6 mm) beyond the hard stoparrangement 260. In other words, the thickness T1 of the sealarrangement 240 is at least about 0.1 inches (2.5 mm) to 0.3 inches (7.6mm) greater than the thickness T2 of the hard stop arrangement 260. Thehard stop arrangement 260 provides for a hard contact against the tubesheet 250, FIG. 7, as the V-packs 94, 95 are moved into position. Forthe preferred V-pack 94, 95, FIG. 19, the hard stop arrangement 260comprises a metal such as steel. Most preferably, the seal arrangementmaterial is polyurethane, having a thickness of at least 0.40 inches inextension outwardly from the surface 265 of the V-pack frame 199.

D. The V-Pack Retention System of U.S. Ser. No. 09/325,697

According to U.S. Ser. No. 09/325,697, when the V-packs 94, 95 areoperatively positioned, FIG. 6, each V-pack 94, 95 is under a force ofcompression, in the direction of arrows 270, 271, respectively, towardthe tube sheet 250. To maintain sealing around the seal arrangements240, retention systems 280 provide a force of compression.

Referring to FIGS. 22-25 of U.S. Ser. No. 09/325,697, the retentionsystems 280 each include a base structure 281, a control arm 282, amoveable seat 283, and an adjustable lift link arrangement 284.

In operation, when the control arm 282 is in the raised position, theseat 283 is raised upwardly in the direction of arrows 270, 271, FIG. 6,causing a pressuring of the V-packs 94, 95 against the tube sheet 250.When the control arm 282 is lowered, under hand operation, in thedirection of arrow 288 the seat 283 is dropped, releasing the sealingpressure. The seat 283 is configured so that when the control arm 282 isdropped, a V-pack 94, 95 can be slid into and out of the seat 283.

Attention is directed to FIG. 10 of U.S. Ser. No. 09/325,697. In FIG. 10an enlarged, front elevational depiction of the lower chamber 21 isdepicted. In FIG. 10, the chamber 21 is shown with the front doorremoved for viewing internal constructions and components. Also, in FIG.10, the chamber 21 is depicted with the V-packs 94, 95 present. Further,in FIG. 10, the retention system 280 is depicted in the raised or liftedconfiguration. FIG. 11 is a side view of FIG. 10, taken from thedirection of arrow 300.

In FIGS. 22-25 of U.S. Ser. No. 09/325,697, the base structure 281,control arm 282, and seat 283 of the retention system 280, are morereadily viewed, especially the details of the seat 283. The seat 283comprises a bottom panel 301 with opposite spaced side flanges 302 and303. The bottom 301 includes a front edge 304, toward which a V-pack 94,95, FIG. 6, is moved, during loading. Projecting outwardly from thefront edge 304, each of the side flanges 302, 303 includes an outwardlydirected guide flange 305, 306, respectively. The guide flanges 305, 306preferably project at an angle F, FIG. 23, of about 120 to 170°,relative to the plane of the associated side flange 302, 303. Preferablythe angle F is within the range of about 135 to 155°. Each guide flange305, 306 is preferably about 0.25 inches (6.4 mm) to 2 inches (51 mm)long. The guide flanges 302, 303 help the centering of the V-pack 94,95, as it is being slid into position.

The base bottom panel 301 includes four rectangularly spaced apertures309 and a central large aperture 310. The four rectangularly positionedapertures 309 circumscribe rotatable wheels 312. The wheels 312 arerotatably mounted on the retention system 280 and raise and lower withthe seat 283, when the control arm 282 is raised and lowered,maintaining the same relative vertical position between the wheels 312and the bottom plate 301. The wheels 312 project above the bottom plate301 at least about 0.03 inches (0.8 mm) and preferably about 0.06 inches(1.5 mm) to 0.15 inches (3.8 mm), so that the V-packs 94, 95 can berolled into place on the base 301 in a convenient manner.

Referring to FIG. 24 of U.S. Ser. No. 09/325,697, the retention system280 comprises a link arrangement 284 including a plurality of links 317.Preferably the links 317 form a parallelogram linkage system 318, sothat during actuation by movement of the control arm 282, the plate 301and the wheels 312, FIG. 22, are lifted or lowered without being tiltedout of their selected plane of mounting. Also, preferably the links 317,and thus the parallelogram linkage system 318, are configured to operateslightly “over center” so that when the control arm 282 is raised, theretention system 280 will tend to retain the raised, locked position.Cushioning to allow the slight “over center” action, is allowed by aspringing action in the links 317.

More specifically, the links 317 are pivotally mounted to a frame 320that is itself pivotally mounted to a lower end 321 of the control arm282. When the arm 282 is lowered, by movement in the direction of arrow288, the base structure 281 is pivoted forward (in the direction ofarrow 313) and downwardly (in the direction of arrow 288), the downwardmotion being caused because the control arm 282 is not only pivotallymounted on the framework 320, but also to a link 326 and a pivot 327.The base structure 281, then, under the control of the links 317, willslide forward and downward. This would move any V-pack 94, 95, FIG. 6,mounted on the seat 283 similarly forward and downward, i.e. out ofsealing contact with the tube sheet 250, FIG. 10, for convenienthandling of the V-packs 94, 95.

E. The Dust Ejector Valve Arrangement of U.S. Ser. No. 09/325,697

The arrangement shown in FIG. 9, and 12-14 of U.S. Ser. No. 09/325,697,includes an elongated dust ejector valve arrangement 160 for removal ofthe dust from the air cleaner assembly 1, FIG. 6. The dust ejector valvearrangement 160 is mounted as part of the bottom 183 of the assembly 1of FIG. 8. The elongated ejector valve arrangement 160 is depicted inthe views shown in FIGS. 9, 12, 13 and 14.

Referring to FIGS. 12 and 13 and according to U.S. Ser. No. 09/325,697,the ejector valve arrangement 160 comprises an assembly 330 including aframe 331 having a plurality of ejector flaps 332 mounted thereon. Theframe 331 includes front and back extensions 334 and 335. The assembly330 includes, extending between front and back, opposite extensions 334and 335, a plurality of angled central panels or extensions 336.Referring to FIG. 14, the central extensions 336 include opposite endextensions 337 and 338, and three pairs of central extensions 339, 340,and 341.

The end extensions 337 and 338 each include a mounting strip thereon 345and 346 respectively, by which the assembly 330 can be mounted to theside walls 27, 28, respectively, FIG. 1, to depend downwardly from thebottom 183 of assembly 1 of FIG. 8. The mounting can be, for example, bymeans of bolts, 350, FIG. 6, or by similar constructions.

The extensions 337 and 338, as well as central pairs 339, 340 and 341,each include a slanted portion defining or having an aperture or awindow 353, FIG. 13, therein. Mounted on an underneath side 354 of eachwindow 353, is a flexible flap 332, FIG. 14. Each flap 332 is securedalong an upper edge 358, FIG. 14, and is pressed against the window 353.In general, the flexible material of the flaps 332 will preferably berubber.

In typical use, as air moves through the first chamber 21, FIG. 9, aslight reduction in pressure within the first chamber 21 relative toambient occurs. This will tend to draw or pull the flexible flaps 332closed, over the windows 353 and against the sides 354. On the otherhand, as a reverse pulse is directed through chamber 21, during a pulsejet operation as described herein, pressure within the first chamber 21momentarily increases, biasing one or more of the flaps 332 away fromthe windows 353 (in a hinged motion along hinge lines 360), and allowingdust to be ejected from within the first chamber 21, downwardly and outof the bottom 183 of the assembly 1 of FIG. 8.

F. The Pulse Cleaning System of U.S. Ser. No. 09/325,697

Attention is directed to FIGS. 10 and 11, from which a more detailedunderstanding of the pulse jet cleaning system will be understoodaccording to U.S. Ser. No. 09/325,697. In general, the pulse jetcleaning system uses pulses of air to clean the V-packs 94, 95. FIG. 10is a fragmentary, schematic, front elevational view of the lower chamber21 and the reverse pulse cleaner arrangement 154 with portions removedfor viewing internal constructions and components. FIG. 11 is analogousto FIG. 10, taken generally from the view point of arrow 300, FIG. 10.Attention is also directed to FIG. 8, in which the portions of theassembly 1 depicted in FIGS. 10 and 11, can be viewed in perspective.

Referring to FIGS. 8, 10, and 11, the pulse cleaner arrangement 154comprises a central tank 152, shown generically in FIGS. 8, 10, and 11and described more particularly with reference to FIGS. 28-31, having aplurality of pulse jet valves 365, 366, 367, 368 mounted thereon, eachvalve having an associated one of nozzles 162-165, respectively,thereon. The particular arrangement 154 depicted in FIG. 8 includes fourvalves, although other arrangements are possible. The valves 365-368 canbe viewed as divided into two pairs; a first pair 370 associated withthe first one of the V-packs 94, FIG. 10, and a second pair 371associated with the second one of the V-packs 95, FIG. 10.

Mounted at the air outlet of each valve 365-368 is a nozzle 162-165including a splitter 157, which comprises a first angled member 375 anda second angled member 158 that cause the air stream released by thevalve to be spread or dispersed, as it enters the V-pack 94 or 95.

In general, according to U.S. Ser. No. 09/325,697, a preferred splitterangle, or angle H, with respect to normal, for the first and secondangled members 375, 158 will be within the range of 2 to 45°, typicallyabout 7 to 30°. In general, the splitters 157 for each pair (370 and 371respectively) are positioned such that their center lines or verticesare spaced apart about 5 to 10 inches (13-25 cm), typically about 6 to 9inches (15-23 cm).

In general, according to U.S. Ser. No. 09/325,697, the reverse pulsesystem 154 can be operated using the air compressor provided by thevehicle manufacturer in the vehicle in which the assembly 1 is mounted.That compressor can be used to charge the charge tank, or storage tank,indicated at 152. Periodically, preferably using a logic control systemas described hereinbelow, the valves 365-368 can be operated to allow apulse jet to pass through the splitters 157 and into the V-packs 94, 95.Preferred sequencing and timing for the pulse jets are described below.In general, the pulse jet of air is directed in a reverse direction,backwards, or as a back flush through the V-packs 94, 95. By the term“in a reverse direction,” it is meant that the pulse jet of air isdirected opposite to normal air flow (i.e., filtering air flow) duringfiltering of ambient air. Such a direction of air flow will tend toflush dust or other particles collected on the V-packs 94, 95 therefrom.

The pulse jet system 154 may, in general, except for the particularpreferred geometric configurations described and shown herein, besimilar to the arrangements described in U.S. Pat. Nos. 4,364,251,4,331,459, and 5,575,826 incorporated herein by reference.

Referring to FIGS. 10 and 16, to facilitate appropriate directing of thepulse jet into the V-pack arrangement, the assembly 1 includes,positioned between the nozzles 162-165, FIG. 8, and the V-packs 94, 95,a preferred rim arrangement 380. For the assembly 1 shown in FIGS. 6 and10, which comprises two V-packs 94, 95 aligned parallel to one another,the rim arrangement 380 comprises first and second rims 381 and 382. Forthe particular assembly 1 shown, the rims 381, 382 are generally thesame, one associated with each V-pack 94, 95.

In general according to U.S. Ser. No. 09/325,697, the second rim 382comprises first, second, third, and fourth extensions 383, 384, 385, and386 that project or extend from the tube sheet 250, FIG. 16. Preferably,each extension 383-386 includes a base flange 387 for attachment to thetube sheet 250 around the aperture 100. The base flanges 387 may beattached, for example, by welding to the tube sheet 250. Preferably, thesecond rim 382 is arranged and configured to surround the aperture 100.

In the particular embodiment illustrated in FIGS. 10 and 16 of U.S. Ser.No. 09/325,697, the second and fourth extensions 384, 386 extend fromthe tube sheet 250 at an angle G with respect to a perpendicular, ornormal, line to the tube sheet 250. Preferably, the angle G is at least2°, and typically is between 4° and 10°, most preferably is about 8°.Angling the second and fourth extensions 384, 386, enhances the captureof the pulse jet air flow from the pulse jet valves 365, 366, FIG. 8, byincreasing the overall size of the aperture 100 and by extending theopening of the aperture 100 closer to the pulse jet valves 365, 366.Angling the second and fourth extensions 384, 386 also reduces thepressure loss due to separation of the air flow in the direction ofarrow 270, FIG. 6, by providing a more gradual expansion of the air flowas it passes from the first chamber 21 to the second chamber 22 throughthe first aperture 100. Furthermore, the rims 381, 382 providestructural rigidity to the tube sheet 250.

The first rim 381 has structure analogous to the second rim 382.

G. The Second Stage Air Cleaner of U.S. Ser. No. 09/325,697

Referring to FIG. 6, in general, according to U.S. Ser. No. 09/325,697,the second stage air cleaner 25 positioned in chamber 22 is constructedas follows. Referring to FIG. 8, projecting into the interior of chamber22 from interior rear wall 390 is a circular mounting flange or tube391. The outer surface 392 of the tube 391 is a surface against whichthe primary element 124, FIG. 17, seals, during assembly (see FIG. 27).The inner surface 393 of the tube 391 is the surface against which thesafety element 125, FIG. 18, seals, during assembly (see FIG. 27).

A preferred primary element 124 is depicted in FIG. 17 of U.S. Ser. No.09/325,697. The primary element 124 comprises first and second oppositeend caps 395 and 396 with filter media 397 extending therebetween. Theparticular element 124 depicted includes inner 398, FIG. 27, and outerliners 399, although in some applications one or both of these linersmay be absent. The end cap 395 is open. A typical end cap constructionis described in U.S. Pat. No. 5,897,676, incorporated herein byreference. The end cap 395 includes a radial sealing region 400positioned therein. In operation, the radial sealing region 400 sealsagainst an outer surface 392, FIG. 27, of the mounting tube 391preferably using a radial seal construction system such as thatdescribed in EP 0329659, the disclosure of which is incorporated hereinby reference. Preferably the end cap 396, FIG. 17 of U.S. Ser. No.09/325,697, is a completely closed end cap, having no apertures therein.

According to U.S. Ser. No. 09/325,697, a variety of materials orcombinations of materials can be utilized for the media 397. In general,what is required is an appropriate media to achieve a preferred level ofefficiency for the filter element 124.

In general, it is anticipated by U.S. Ser. No. 09/325,697 that for manypreferred arrangements, the media 397 will comprise a pleated media suchas cellulose. If desired, such media can be improved, for overallefficiency, by providing thereon a deposit or layer of “fine fiber”material, typically a material having an average fiber diameter of 5microns or less.

One particular commercially used media comprising a fine fiber depositedonto a paper or cellulose material is practiced by Donaldson Company,Inc., the assignee of the present application, in products generallyidentified under the trademark EON™. These media are manufactured by atrade secret process of Donaldson's. Such media would be useable inarrangements according to the present invention.

One useable media, according to U.S. Ser. No. 09/325,697, is a mediahaving a frazier permeability within the range of 14.0-18.0 ft/min.(7.1-9.1 cm/sec) and a thickness of about 0.009-0.013 inches (0.2-0.3mm). Generally, the media will be pleated with the selected pleat depthdepending on the particular application. In general, the pleat depthselected will be at least 0.5 inches (1.3 cm), preferably about 0.75 to2 inches (2-5 cm), and most preferably about 1 inch (2.5 cm) to 1.25inches (3.2 cm). Pleating, and sealing into a cylindrical configuration,can be conducted utilizing standard, conventional pleat and sealingtechniques.

Still other media configurations usable for the element 124 are foammedia, fiberous media, or combinations of pleated media with one or moreof foam media or fiber step media. Various usable combinations includethose described in U.S. Pat. Nos. 5,622,537 and 5,672,399, incorporatedherein by reference. The particular media chosen for any givenapplication will, in general, be a function of desired efficiency versuscontaminant challenge.

A variety of materials may be utilized for the inner and outer liners398, 399, FIG. 27 of U.S. Ser. No. 09/325,697, and the same material maynot be used for both. In some instances, expanded metal, perforatedmetal, or plastic materials will be preferred. It is noted that for adesirably functioning radial seal, preferably a portion of the innerliner 398 in region 400, is positioned to operate as a support, backingup the pressing of the end cap 395 in radial seal region 400, duringsealing. This is shown in EP 0329659.

For the particular assembly 1 depicted, the assembly 1 includes a tube134, FIG. 6, projecting therefrom. The tube 134 allows for thepositioning, within chamber 22, of the primary element 124 which islonger than the distance between rear wall 29 and front wall 3, FIGS.1-3. As explained previously, the cover 6, for access to the element124, is positioned on an end of tube 134.

Attention is directed to FIG. 18 of U.S. Ser. No. 09/325,697. In FIG. 18the safety element 125 is depicted according to U.S. Ser. No.09/325,697. The safety element 125 generally comprises media 420extending between opposite end caps 421 and 422. The safety element 125includes an inner liner 423, FIG. 27, and an outer liner 424, alsoextending between end caps 421 and 422.

The end cap 422 is a closed end cap, closing one end of the media 420and the liners 424 to the passage of air therein. As a result, the media420 defines an open central area 426, FIG. 27.

The end cap 421 includes a ring 428 of soft, pressible material thereon,constructed and arranged to fit within the tube 134, FIG. 6, to sealagainst inner surface 393, FIG. 27, of the tube 391 in use. Preferablyaccording to U.S. Ser. No. 09/325,697, the safety element 125 is sizedand configured to fit underneath the primary element 124, when mounted,see for example FIG. 27.

Conventional materials and configurations can be utilized with thesafety element 125. With respect to the principals of the presentinvention, there is no specific preference with respect to the materialsof the safety element 125, other than general preferences forconveniently manufactured, efficiently constructed materials.

In general, it is anticipated by U.S. Ser. No. 09/325,697 that for manypreferred arrangements, the media 420 will comprise a pleated media suchas cellulose. Other media configurations usable for the element 125 arefoam media, fiberous media, or combinations of pleated media with one ormore of foam media, or fiber step media. Various usable combinationsinclude those described in U.S. Pat. Nos. 5,622,537 and 5,672,399,incorporated herein by reference. The particular media chosen for anygiven application will, in general, be a function of desired efficiencyversus contaminant challenge.

According to U.S. Ser. No. 09/325,697, a variety of materials may beused for the inner 423 and outer liners 424, and the same material maynot be used for both. In some instances, expanded metal, perforatedmetal, or plastic materials will be preferred. It is noted that for adesirably functioning seal, preferably a portion of the outer liner 424,FIG. 27, is positioned to operate as a support, backing up the pressingof the end cap 421 during sealing.

H. The Charge Tank of U.S. Ser. No. 09/325,697

Attention is directed to FIGS. 28-31 of U.S. Ser. No. 09/325,697. FIG.28 is a schematic, perspective view of an example embodiment of a chargetank 552 useable as the tank 152 in the assembly of FIG. 10. FIG. 29 isa schematic, top plan view of the charge tank 552. FIG. 30 is aschematic, cross-sectional view of the charge tank 552 of FIG. 29, takenalong line 30-30. FIG. 31 is a schematic, cross-sectional view of thecharge tank 552 of FIG. 29, taken along line 31-31.

Referring to FIGS. 1 and 28. Preferably, according to U.S. Ser. No.09/325,697, the charge tank 552 includes first and second attachmentplates 581, 582. Typically, the charge tank 552 extends from the frontside 3 of the assembly 1 to the rear side 12, FIG. 3, of the assembly 1.The second attachment plate 582 includes four bolts 583 andcorresponding bolt holes (not shown). Likewise, the first attachmentplate 581 includes four bolts (not shown) and corresponding bolt holes(not shown). In the embodiment illustrated in FIG. 1, the charge tank552, FIG. 28, is bolted to the inside of the front side 3 of theassembly by the bolts 583. The second attachment plate 582 is locatedbehind the front side 3 of the assembly 1. The bolts 583 extend throughthe front side 3 and the second attachment plate 582, securing thesecond attachment plate 582 to the front side 3 of the assembly 1, andcorrespondingly securing the charge tank 552 to the assembly 1.Analogously, the first attachment plate 581 is secured to the rear side12 of the assembly 1 of FIG. 1. Of course, the charge tank 552 may beattached by other means, for example, by welding.

Attention is directed to FIGS. 29-31 of U.S. Ser. No. 09/325,697. In theembodiment illustrated and described in U.S. Ser. No. 09/325,697, thecharge tank 552 is generally cylindrical having an inside diameter D1,FIG. 30, and a length L1, FIG. 29. The charge tank 552 defines aninterior air pressure chamber 584. The air pressure chamber 584 isconstructed and arranged to contain pressurized air. The charge tank 552includes an inlet 585, FIG. 31. The inlet 585 is constructed andarranged to be connected to the vehicle's air pressure tank (not shown)via, for example, an air pressure tube (not shown). Preferably, thevehicle's air pressure tank is used to pressurize the charge tank 552with air.

Referring to FIG. 30, in the embodiment illustrated and described inU.S. Ser. No. 09/325,697, the charge tank 552 is connected to a pulsecleaning system 554, analogous to the pulse cleaning system 154 of FIG.6. The pulse cleaning system 554 includes a plurality of pulse valves553. The charge tank 552 is connected to the pulse valves via conduits588. Through the conduits 588, pressurized air communicates between thecharge tank 552 and the pulse cleaning system 554 for discharge from thepulse valves 553 for cleaning of the V-packs 94, 95, FIG. 6.

Occasionally, water condensation will collect within the charge tank552. Preferably, the charge tank 552 includes a water condensationdischarge system 586 for removing the water condensation from the chargetank 552. In the embodiment illustrated in FIG. 30, the discharge system586 includes a tube 587 connected to one of the pulse valves 553. Thetube 587 is constructed and arranged to withdraw any accumulated water,from the water condensation, from the bottom 589 of the chamber 584.During firing of the pulse valves 553, pressurized air passes from thecharge tank 552 to the pulse valves 553 via the conduits 588. Thepressurized air gathers near the top of the chamber 584 while theaccumulated water gathers in the bottom 589 of the chamber 584. As thewater accumulates, the water forms a seal about a first end 590 of thetube 587. As the pressurized air passes through the conduit 588, avacuum is created in the discharge tube 587. The vacuum draws theaccumulated water out of the bottom 589 of the chamber 584 anddischarges the water through the pulse valve 553.

I. The Control Logic and Programming

In this section, some preferred control logic and programming logic foroperation of the pulse cleaning system 154, FIG. 6, is provided. Fromthe principles described in U.S. Ser. No. 09/325,697, a variety ofcontrol systems can readily be designed. The particular examplesprovided herein are intended as examples. It will be apparent that theoperation of the pulse cleaning system 154 can be accomplished withconventional electronic system techniques.

Referring to FIG. 6, in the particular embodiment illustrated anddescribed in U.S. Ser. No. 09/325,697, the control system selected willin part be defined by the restriction down-stream of the V-packs 94, 95relative to ambient pressure. The restriction is equal to the pressuredifferential, or drop, across the V-packs 94, 95 plus the inlet staticpressure losses. By the term “pressure differential,” it is meant thedifference in pressure up-stream of the V-packs 94, 95 versus thepressure down-stream of the V-packs 94, 95, i.e., the pressure in theclean air plenum 99 of the V-packs 94, 95. This restriction provides arelative measure of the efficiency of the operation of the V-packs 94,95. As the V-packs 94, 95 become occluded with particulate matter, therestriction for the V-packs 94, 95 increases. The air pressures aretypically measured using air pressure measuring devices commonly known.

In alternative embodiments, the clean air pressure may be measuredanywhere down-stream of the V-packs 94, 95, for example in the clean airplenum 99 of the V-packs 94, 95. The ambient air pressure may bemeasured any where up-stream of the V-packs 94, 95, for example outsideof the housing 20.

In the particular embodiment illustrated, the control system activates acleaning cycle when the restriction down-stream of the V-packs 94, 95reaches a particular level. With typical equipment such as heavy haultrucks, it is generally considered important by the original equipmentmanufacturers that the restriction for the entire air cleaner assembly 1not exceed approximately 25 inches (64 cm) of water. In general, throughempirical observation, it has been determined that the pulse cleaningsystem 154 should preferably be activated when a restriction is measuredof preferably between 16 and 20 inches (41-51 cm) of water, and mostpreferably about 16 inches (41 cm) of water. A reason for this is thatif the pulse cleaning system 154 is prevented from operation until therestriction reaches 25 inches (64 cm) of water, the pulse cleaningsystem 154 will be less efficient in refurbishing the associated V-packs94, 95 for relatively long operation. Alternately stated, in general,the pulse cleaning system 154 does not remove all particulate materialfrom the associated V-packs 94, 95. Thus, with repeated cycles, forexample 10 cycles, the ability of the pulse jet cleaning system 154 tomaintain operation of the V-packs 94, 95 below the overall restrictionof about 25 inches (64 cm) of water is reduced. In general, it isbelieved that when the pulse cleaning system 154 can no longer keep therestriction below about 20 inches (51 cm) of water, change-out of theassociated V-packs 94, 95 is desirable.

In general, it will also be preferred to actuate the pulse valves 153 tocause the pulse jet cleaning to occur, when the engine system is notunder significant load and the airflow through the assembly 1 isrelatively low. Alternately stated, for example, when the equipment is avehicle, it will be preferred that the pulse jet cleaning system 154 beactuated to clean the V-packs 94, 95 when the vehicle is in neutral andthe engine is in idle, or at least when the engine is operating at arelatively low rpm (1500 rpm or less). In general, preferred logiccontrol systems will monitor engine rpm, with respect to operation.Thus, determining whether the engine is in an “idle” condition or someother condition for operation, or prohibiting operation, will typicallyturn on determination of the engine rpm. A reason for this is when theengine is under significant load demands, the air flow demands aresubstantially greater. Since the normal engine air flow works in theopposite direction of the pulse cleaning system 154, it will in generalbe harder to clean, and the cleaning will be less effective, when theengine is under significant load rather than when the engine is at ornear idle.

In some instances, however, if a significant amount of time (10 minutesor more) has elapsed and the engine idle (or low rpm) condition has notoccurred, it may be desirable for the control system to have an“override” that will cause the pulse cleaning to occur in spite of thefact that the engine idle (or low rpm) condition has not been reached.

Given the above observations, a preferred logic control system issuggested. Attention is directed to FIG. 32. Preferably, the logiccontrol system 499 would be in accord with the reasoning of the flowchart illustrated in FIG. 34. Still in reference to FIG. 32, in general,the intent of the logic control system 499 is to optimize the cleaningof the V-packs 94, 95 by firing the pulse valves 365-368, FIG. 8, at thelowest engine air flow (by sensing rpm). However, at the end of acleaning time period, even if the rpm is higher, the system 499 willcontinue to fire the pulse valves 365-368 regardless to preventabnormally high restrictions across the V-packs 94, 95. Preferably, thelogic control system 499 receives signals from the vehicle regarding theengine speed, vehicle tank pressure switch, the service switch, and theenable switch. The logic control system 499 also receives signals forthe accumulator tank pressure and the air cleaner restriction. The logiccontrol system 499 systematically fires the pulse valves 365-368 toclean the V-packs 94, 95, based on these inputs.

FIG. 32 is an electrical schematic generally depicting the interfacesbetween the control system 499, the vehicle, and the air cleaner 1,FIG. 1. In general, the system 499 is controlled by a controller 500.Preferably, the controller 500 located within the housing 20, FIG. 20.In some instances, the controller 500 might be positioned outside of thehousing 20, for example, in the vehicle itself. In other instances, thecontrol logic of the controller 500 might be in a part of the vehicle'sengine management system.

The controller 500 is in electrical communication with an instrumentpanel 502 of the vehicle. Preferably, the controller 500 receives powerthrough a first electrical connection 504, for example wires.Preferably, the electrical connection is a male Deutsch HD34-18-14PN. Ofcourse, any suitable connector could be used. The first electricalconnection 504 passes through a fuse 506, typically 5 amps (18,000coulombs). The fuse 506 protects the controller 500 from high amperagethat may damage the controller 500 or wires. A second electricalconnection 508 provides for the controller's 500 return current.Preferably, the controller 500 draws power from the vehicle's 24 volt dcpower supply at a rate of 0.1 amperes (360 coulombs) during operation.When a pulse valve fires, the current increases to about 0.5 amperes(1800 coulombs) for about 0.1 seconds. Preferably, there is a voltagespike protection on the electrical inputs to prevent damage to the inputcircuits of the controller 500. The inputs are voltage clamped at 5volts (0.02 statvolts) and the current is limited with a 470 ohm (470ohm) resistor or greater. The logic circuitry operates from a 5 volt(0.02 statvolts) supply that is regulated by a LM2940T-5.0.

In the particular embodiment illustrated and described, the controller500 is electrically connected to a service lamp 510 via a thirdelectrical connection 512. Preferably, the service lamp 510 is installedon the dash of the vehicle for an operator's inspection. Generally, whenthe air cleaner assembly 1 is malfunctioning, the service lamp 510 willilluminate, indicating to the operator that something is wrong with theair cleaner assembly 1.

The service lamp 510 indicates to the user that either something in thesystem is preventing cleaning of the V-pack filters 94, 95, i.e., nopower, no engine rpm, or a cleaning system failure, or that the V-packfilters 94, 95 require servicing. Preferably, the user can determinewhat the fault that caused the service light to come on is by activatingthe service switch, for about 5 seconds and then releasing. Serviceinformation can then be indicated to the user by a series of flashes andpauses. For example, a first flash of 0.1 seconds, a pause of 5 seconds,and a pair of two short flashes (0.1 seconds) might indicate anelectrical problem with the first pulse valve. Two short flashes 1.5seconds apart, a pause, and a pair of two short flashes at the end mightindicate an electrical problem with the second pulse valve.

Of course any series of flashes, pauses, or steady lights can be used toindicate a number of faults with the system through the service lamp.Alternatively, a user could connect a computer to the controller 500through the RS-232 connector. Signals regarding the fault are sent tothe computer through this connection.

In some instances, a dual housing or quad housing might be used on thesame vehicle. In these instances, the inhibit function, described below,prevents each unit from pulsing while another unit is pulsing. Also, inthese instances, each unit could have its own service switch forindicating faults to a single service lamp. Alternatively, a separateservice lamp for each unit might be used.

In the particular embodiment illustrated and described, the controller500 is also electrically connected to an engine rpm sensor 513 viaelectrical connection 514. The engine rpm sensor 513 allows thecontroller 500 to monitor the engine rpm. The controller 500 iselectrically connected to a service switch 516 via electrical connection518.

In the particular embodiment illustrated and described, the controller500 is electrically connected to the pulse valves 365-368 via electricalconnections 520, 521, 522, and 523, respectively. This allows thecontroller 500 to fire the pulsevalves 365-368 as appropriate. Thecontroller 500 is also electrically connected to the charge tank oraccumulator 152 via electrical connection 525, a restriction sensor 530,and the vehicle's air pressure tank 529 via electrical connection 531.The controller 500 is connected to a clean inhibit line 540 from anotherair cleaner controller via electrical connection 541. The clean inhibitline 540 is used when more than one air cleaner assembly 1 is configuredon one vehicle. The controller 500 is also connected to an enable signal519. The enable signal 519 is used to enable the pulsing operation or todisable the pulsing operation from the vehicle.

In the particular embodiment illustrated and described, the controller500 includes an interface port 532. In one embodiment this interface isan RS-232 interface. This port 532 allows an operator interface, forexample to a computer, to modify the logic control of the control system499 by the operator or to receive output from the controller 500.

Attention is directed to FIG. 33. FIG. 33 is an electrical schematicgenerally depicting greater detail of an example embodiment of thecontroller's 500 interface with the rest of the control system 499illustrated in FIG. 32. Module 560 illustrates the interface with theservice light 510, FIG. 32. Module 596 illustrates the interface withthe clean inhibit line 540, FIG. 32. Module 590 illustrates theinterface with the charge tank 152, FIG. 32. Module 580 illustrates theinterface with the restriction sensor 530, FIG. 32. Module 579illustrates the interface with vehicle pressure tank 529, FIG. 32.Module 563 illustrates the interface with the engine rpm sensor 513,FIG. 32. Module 566 illustrates the interface with the service switch516, FIG. 32. Module 569 illustrates the interface with the enablesignal 519, FIG. 32. Module 595 illustrates the interface with theRS-232 port 532, FIG. 32. Module 552 illustrates the interface with thevehicle instrument panel 502, FIG. 32, for vehicle electrical 24 volt dcpower. Modules 591, 592, 593, 594 illustrate the interfaces with thepulse valves 365, 366, 367, 368, respectively.

Attention is directed to FIG. 34. FIG. 34 is a flow chart illustratingthe preferred logic operation of the control system 499, FIG. 32.Referring now to FIG. 34, the logic control begins at block 400. Atblock 402, the controller 500 starts-up and sends electrical pulses, ora heart beat, to the module 560, FIG. 32, providing an indication thatthe controller 500 is working. At block 404, the controller 500 performsa system check for errors. For example, if the heartbeat is not receivedbecause of an inoperative controller 500, the service light 510, FIG.32, is turned on at block 406. If no error is detected, at block 408 thecontroller 500 acquires inputs from the equipment, such as the rpm ofthe engine. At block 410, the controller 500 checks the service switch516 activation, FIG. 32, any service codes received during the lastoperation, and the enable signal. At block 412, the controller 500determines if the enable signal 519, FIG. 32, is active.

If the enable signal 519 is inactive, the controller 500 outputs data atblock 414 to a RS-232 interface port 532, FIG. 32, which may beconnected to another computer. At block 416, the controller 500 checksfor any terminal input from an operator interface, such as a computerconnected to the RS-232 interface port 532. At block 418, the controller500 determines if the input received from the RS-232 interface port isout of range. For example, the software loaded on the controller may bemenu-driven having six menu choices. If a #7 is received, the input isout of range. If the input is not out of range, the controller 500determines at block 420 if the cleaning cycle has been triggered. Atblock 422, the cleaning cycle has been triggered, the controller 500changes a state flag from 0 to 2 and returns to block 400 via block 424.If the cleaning cycle has not been triggered, the controller 500 atblock 426 determines if the logic is a terminal mode, i.e., a computeris connected to the RS-232 port. If not, a pulse valve is firedcorresponding to a number input from the RS-232 port at block 428. Forexample the numbers 1-4 may correspond to pulse valves. If 1 is pressed,the controller 500 fires the first pulse valve at block 428. If thesystem 429 is in a terminal mode, the controller 500 enters the terminalmenu at block 430. The logic then proceeds to block 424.

Returning to block 412, if the enable signal 519, FIG. 32, is active,the controller 500 checks the controller 500 state at block 432. Atblock 434, the controller 500 determines if the state is equal to 0. Ifthe state is equal to 0, at block 436, the controller 500, or a pressuredrop component of the controller 500, determines if the restriction downstream of the V-packs 94, 95, FIG. 6, is greater than a thresholdrestriction, for example 16 inches (41 cm) of water. If the restrictionis not greater, the logic control proceeds to block 414.

If the restriction is greater, the controller 500 determines if thelockout flag is on at block 438. This flag is set on at the applicationof power to the controller 500 or at vehicle start-up. If the lockoutflag is on, block 440, the controller 500 sets the lockout 516 to off.At block 442, the controller 500 changes the state to 1. At block 444,the controller 500 checks a lockout delay timer. For example, this timermay not allow pulsing for two minutes, after a restriction greater thanthe threshold restriction is detected. At block 446, the controller 500determines if the delay timer has timed out, or for example, the twominutes is up. This is a safety device to prevent pulsing duringservicing. If the delay timer has not timed out, logic control proceedsto block 414. If the delay timer has timed out, the controller 500 setsthe state to 2 at block 448. Flow proceeds to block 450 where thecontroller 500 checks for an inhibit flag.

Referring back to block 438, if the lockout delay is not on, thecontroller 500 proceeds to block 448. This is the normal logic path. Thelogic control proceeds as described above. Referring back to block 434,if the state does not equal 0, the controller 500 determines if thestate is equal to 1 at block 452. If the state is equal to 1, flowproceeds to block 444 and the logic control proceeds as described above.If the state is not equal to 1, the controller 500 determines if thestate is equal to 2 at block 454.

Referring to block 450, logic flow proceeds to block 456 where thecontroller 500 determines if the inhibit line is active from anothercontroller. If the inhibit line is active, flow proceeds to block 414.If the inhibit line is not active, the controller 500 sets the state to3 at block 458. At block 460, the controller 500 activates the inhibitout. In some applications multiple air cleaners, such as the air cleaner1 of FIG. 1, may be utilized on one vehicle. For example, in a two aircleaner, two controller environment, the controller 500 sends an inhibitsignal to the other controller to prevent the other controller fromfiring a pulse valve when the controller 500 is firing a pulse valve.This ensures maximum air pressure for each pulse valve firing. Also, itprevents overloading the vehicle's air supply system.

Referring back to block 454, if the state does not equal 2, thecontroller 500 determines if the state is equal to 3 at block 462. Ifthe state is equal to 3, flow proceeds to block 460. At block 464, thecontroller 500 checks a charge tank delay timer. For example, a timermay be set for 10 seconds to allow the charge tank 152, FIG. 32, torefill prior to the next pulse valve firing. At block 466, thecontroller 500 determines if the accumulator charge delay timer is timedout, i.e., ten seconds has passed. If not, logic flow proceeds to block414. If the accumulator charge delay timer has timed out, the controller500 sets the state to 4 at block 468.

At block 470, the controller 500, or an engine load component of thecontroller 500, determines if the rpm is below a threshold rpm, forexample 1200 rpm via the rpm sensor 513, FIG. 32. Referring back toblock 462, if the state does not equal 3, flow proceeds to block 470. Ifthe rpm is not below the threshold level, the controller 500 checks anrpm adjust timer at block 472. For example, the rpm adjust timer may beused to increase the rpm threshold trigger level over time. If an amountof time has elapsed, i.e., ten minutes, the controller 500 will adjustthe threshold rpm level. At block 474, the controller 500 determines ifthe rpm adjust timer has timed out. If not, flow proceeds to block 414.If the adjust timer has timed out, the controller 500 increments the rpmthreshold level by 100 rpm at block 475, for example, the threshold rpmis now 1300 rpm. At block 476, the controller 500 determines if the rpmadjust time should be shortened. For example, after the initial 10minutes, an rpm adjust time may be shortened to 5 minutes. If yes, flowproceeds to block 414. If not, the controller 500 shortens the rpmadjust time at block 477 to, for example, 5 minutes. Logic flow proceedsto block 414.

Referring back to block 470, if the rpm is below the threshold level,the controller 500, or an accumulator pressure component, determines ifthe charge tank 152, FIG. 32, has sufficient pressure at block 478, forexample 90 psi. If not, flow proceeds to block 479. At block 479, thecontroller 500 checks a low pressure timer. For example, the controller500 may wait 30 minutes for the charge tank to fill-up to 90 psi. Atblock 480, the controller determines if the low pressure timer has timedout, i.e., 30 minutes has passed. If not, logic flow proceeds to block414. If the timer has timed-out, the controller 500 turns on the servicelight 510, FIG. 32, at block 481. Logic flow proceeds to block 414.

Referring back to block 478, if the accumulator has sufficient pressure,the controller 500, or a vehicle pressure component of the controller500, determines at block 482 if the vehicle pressure tank is sufficientpressure, for example 95 psi. If not, flow proceeds to block 479. If thevehicle pressure tank is sufficient, the controller 500, or a pulsefiring component of the controller 500, selects the pulse valve to pulseat block 483. At block 484, the controller 500 pulses the valve.Attention is directed to FIG. 35. FIG. 35 is a flow chart illustrating amore detailed, preferred logic of the firing of a pulse valve. At block600, the firing sequence begins. While firing the pulse valve, at block602, the controller 500 clears all error counts. At block 604, thecontroller 500 sets the pulse valve output high. At block 606, thecontroller 500 checks the voltage. At block 608, the controller 500determines if the voltage is too low or high. If the voltage is too lowor high, the controller increments a voltage error count at block 610.Logic flow proceeds at block 612. Referring back to block 608, if thevoltage is correct, at block 612, the controller 500 checks for anelectrical short. If there is an electrical short, the controller atblock 614 increments a short error count. Logic flow proceeds to block616. If there is not an electrical short, at block 616, the controllerdetermines if the current is too low or too high. If so, at block 618,the controller 500 increments the amperage error count. Logic flowproceeds to block 620. If the current is correct, at block 620, thecontroller checks if the pulse time is completed. If not, logic flowproceeds to block 606. Thus, during firing of a pulse valve, thecontroller 500 continually monitors the checks described above. If thepulse time is completed, at block 622, the controller determines if theerror counts are less than 3. If not, at block 624, the controller setsthe error flag and writes to the EE PROM. Logic flow proceeds to block626. If yes, the pulse valve firing is completed at block 626.

Referring back to block 484, FIG. 34, at block 487, the controller 500sets the state to 2. At block 488, the controller 500 determines if thecleaning cycle has been completed. If the cleaning cycle has not beencompleted, the controller 500 deactivates the inhibit at block 489. Forexample, have 40 pulses been fired. If the cleaning cycle has beencompleted, the controller 500 clears the cleaning variables at block490. At block 491, the controller 500 resets the rpm threshold levelback to the initial threshold level, i.e. 1200. At block 492, thecontroller 500 sets the state to 0. Logic flow proceeds to block 489.

In general, according to U.S. Ser. No. 09/325,697, the controller 500monitors the restriction down stream of the V-packs 94, 95. When therestriction down stream of the V-packs 94, 95 is greater than 16 inches(41 cm) of water, the clean cycle is enabled. It is generally preferredthat once the clean cycle is enabled, that the cleaning cycle becompleted within a predetermined amount of time. This is so that thecleaning cycle is completed before the V-packs 94, 95 reach a level ofpressure differential that cannot be cleaned by the pulse system 499, aspreviously described herein. This predetermined time period isempirically determined based on field tests. In general, the amount oftime will be greater than 3 minutes, preferably between 20 minutes and120 minutes, and most preferably between 30 minutes and 90 minutes.

The controller 500 monitors the engine speed. The controller 500determines if the engine speed is less than a first speed, or in otherwords, in a low idle condition for example, 1200 rpms. If the enginespeed is less than 1200 rpms, the controller 500 determines if the airpressure in the charge tank is greater than 90 psi. If the air pressureis greater than 100 psi, the controller 500 checks the vehicle tankpressure. If the vehicle tank pressure is greater than 90 psi, a pulsevalve is fired. When the cleaning cycle is started, a timer is set, forexample at 10 minutes. The controller continues to monitor the rpmsduring the 10 minutes. If after 10 minutes the cleaning cycle has notbeen completed, the controller 500 increments the rpm by 100 to 1300rpm. The timer is reset for 5 minutes. If the cleaning cycle is notcompleted during the next 5 minutes the controller 500 again incrementsthe rpm to 1400. Thus continues until a complete cleaning cycle, forexample 4 valves, ten pulses each, has been completed.

In general, a complete cleaning cycle may be any number of pulse valvefirings. The number of pulse valve firings needed to clean the V-packs94, 95 is empirically determined from field tests and will vary undervarying conditions. Preferably, the cleaning cycle will comprise atleast 4 pulse valve firings, more preferably between 10 and 80, and mostpreferably 40 pulse valve firings. As previously discussed, the amountof time that elapses, between the start of the cleaning mode and thecompletion of the cleaning cycle, varies.

In one particular example, the amount of time that elapses between thestart of the cleaning mode and the completion of the cleaning cycle is60 minutes and the required pulse valve firings is 40. In addition, thethreshold rpm is 1200 rpm, and the rpm increment is 100 rpm.

In alternative embodiments, any number of pulse valve firings, enginespeeds, elapsed time, number of increments (both engine speed andelapsed time) may be utilized in accordance with the principlesdescribed.

The logical operations of the various embodiments described herein canbe implemented (1) as a sequence of computer implemented steps orprogram modules running on a computing system and/or (2) asinterconnected logic circuits or circuit modules within the computingsystem. The implementation is a matter of choice dependent on theperformance requirements of the computing system implementing theinvention. Accordingly, the logical operations making up the embodimentsof the present invention described herein are referred to variously asoperations, steps, engines, blocks, or modules.

II. Comments on Disclosure of U.S. patent application Ser. No.09/325,697

In the disclosure of U.S. patent application Ser. No. 09/325,697subsection C, the media 200 of the V-Packs 94, 95 is discussed. Inparticular, a deposit or layer of polymeric fiber material, or “finefiber,” is discussed. The amount of fine fiber deposited is a matter ofdesign choice for a given application. The method used will be a matterof choice based upon such factors as cost, availability of equipment,and related commercial variables. One usable method is disclosed in U.S.Pat. No. 4,650,506, issued to Barris et al.

III. Additional Disclosure Relating to an Interlock Arrangement

Attention is now directed to FIGS. 36-43. These figures were not presentin U.S. Ser. No. 09/325,697. In FIG. 36, an example embodiment of aV-pack filter 1500 is depicted. The V-pack filter 1500 comprises firstand second panels 1502, 1504, with media 1508 positioned therein, and anouter frame construction 1506. The frame construction 1506 includesfirst and second frame structures, or end caps, 1510, 1511. The firstframe structure 1510 seals a side, or end, orientated as a bottom 1512of the V-pack filter 1500, forcing air through the first and secondpanels 1502, 1504. Attention is directed to FIG. 40. FIG. 40 is abottom, plan view of the V-pack 1500. The first frame structure 1510includes a bottom portion 1510 a. The bottom portion 1510 a includesfirst and second side portions 1510 b, 1510 c and first and second endportions 1510 d, 1510 e extending therefrom. In the particulararrangement shown, the first and second side portions 1510 b, 1510 c andfirst and second end portions 1510 d, 1510 e are approximatelyperpendicular to the bottom portion 1510 a, as illustrated in FIGS. 36and 40.

Referring back to FIG. 36, in the particular embodiment depicted, themedia 1508 of the first and second panels 1502, 1504 is pleated andoriented such that when the V-pack filter 1500 is positioned in thevertical orientation of FIG. 6, the pleats 1514 extend vertically.Having vertical pleats is typically preferred because it aids inknocking the dust of the V-pack filter 1500 during a pulse cycle asdescribed in U.S. Ser. No. 09/325,697.

The V-pack filter 1500 includes first and second opposite end panels1516, 1518. The first and second end panels 1516, 1518 close ends of theclean air plenum 1520 when the V-pack 1500 is operably mounted, orpositioned. By the term “operably mounted,” it is meant that the V-packfilter 1500 is in sealing engagement with a housing, such as the housing1 shown in FIG. 6. Attention is directed to FIG. 37. FIG. 37 is a side,elevational view of the V-pack 1500. For convenience, one of the endpanels 1518 is shown having a handle construction 1522 positionedthereon. The handle construction 1522 is convenient for mounting anddismounting the V-pack filter 1500 and also for carrying the V-packfilter 1500. It should be noted that the other end panel 1516 could alsohave a handle construction or that neither end panel 1516, 1518 wouldhave a handle construction.

Attention is directed to FIG. 37. FIG. 37 is a side elevational view ofthe V-pack filter 1500 of FIG. 36. Preferably, the handle construction1522 is secured in extension between first and second brackets 1525,1526. The handle construction 1522 comprises an extension of wire 1524having first and second end stops 1528, 1530 thereon. When a centralportion 1529 of the flexible wire 1524 is pulled, the handleconstruction 1522 will bow outwardly until the end stops 1528, 1530engage the brackets 1525, 1526, respectively.

The first and second panels 1502, 1504 are oriented in a V-shape, asshown. The first panel section 1502 has first and second ends 1532,1536. Likewise, the second panel section 1504 has third and fourth ends1534, 1538. The first end 1532 of the first panel section 1502 and thethird end 1534 of the second panel section 1504 are oriented eitheradjacent one another or closely spaced and having a first distance T5between them. The second end 1536 of the first panel section 1502 andthe fourth end 1538 of the second panel section 1504 are spread apartfrom one another having a second distance T6 between them. Preferably,the second distance T6 is greater than the first distance T5. That is,preferably the panels 1502, 1504 form a V-shape, most preferably havinga filter angle Z between the panels 1502, 1504, of at least about 5°,preferably within the range of 10 to 25°, most preferably about 13 to17°.

Attention is directed to FIG. 38. FIG. 38 is a top, plan view of theV-pack filter 1500 of FIG. 36. The V-pack filter 1500 preferablyincludes a central spacer 1535 separating the V-pack filter 1500 intoseparate regions 1539, 1540. In use, a separate one of nozzles, forexample the nozzles 162-165 of FIG. 8, is directed into each region1539, 1540. The central spacer 1535 directs the air from each nozzle toan associated region 1539, 1540 of the V-pack filter 1500 to providedirected air sufficient to clean the exterior portions of the panels1502, 1504.

The air flow exit end 1542 of the V-pack filter 1500 includes a sealingarrangement 1543 thereon. Preferably, the sealing arrangement 1543includes a seal ring or gasket 1544 having a first projection thicknessT7, FIG. 37. Referring back to FIG. 37, when the V-pack filter 1500 isoperatively positioned within an air cleaner assembly, such as theassembly 1 of FIG. 7, the seal arrangement 1543 is pressed between anend 1546 of the V-pack filter 1500 and a tube sheet, such as the tubesheet 250 of FIG. 7. In general, the seal arrangement 1543 is sized tobe sealingly positioned around an aperture, such as the aperture 100 ofFIG. 7, in the tube sheet.

Preferably, the V-pack filter 1500 also includes a hard stop arrangement1548 thereon having a second projection thickness T8 less than the firstthickness T7. Preferably the hard stop arrangement 1548 is configured toextend the second thickness T8 of at least about 0.1 inches (2.5 mm),typically about 0.2 inches (5.1 mm) to 0.3 (7.6 mm) inches, above (oroutwardly from) a top surface 1550 of the V-pack filter frameconstruction 1506. Also, preferably the seal arrangement 1543 isselected such that, prior to being pressed, the seal arrangement 1543extends at least about 0.1 inches (2.5 mm) to 0.3 inches (7.6 mm) beyondthe hard stop arrangement 1548. In other words, the thickness T7 of theseal arrangement 1543 is at least about 0.1 inches to 0.3 inches greaterthan the thickness T8 of the hard stop arrangement 1548. The hard stoparrangement 1548 provides for a hard contact against the tube sheet asthe V-pack filter 1500 is moved into operable position. Preferably, thehard stop arrangement 1548 comprises a metal such as steel. Mostpreferably, the gasket material is polyurethane, having a thickness ofat least 0.40 inches in extension outwardly from the surface 1550 of theV-pack filter frame construction 1506.

Referring now to FIG. 39, preferably, an apparatus 1600 includes theV-pack filter 1500 and a retention, or lift, mechanism 1602. Preferably,the retention mechanism 1602 moves the V-pack filter 1500 into itssealing, or operable, position around the aperture in the tube sheet.The retention mechanism 1602 is analogous to the lift mechanism 280 ofU.S. Ser. No. 09/325,697. Preferably, the apparatus 1600 also includes alocking system, or interlocking arrangement, 1603. The locking system1603 is constructed and arranged to help retain the V-pack 1500 in itssealed, or operable, position, when the retention mechanism 1602 ismoved to a first raised, or locked, orientation as described in U.S.Ser. No. 09/325,697. The locking system 1603 also helps to center theV-pack filter 1500 around the aperture 100 and to stabilize the V-packfilter 1500 during operation. The locking system 1603 also preventsinappropriate, i.e. parts not having the required performancecharacteristics, parts from being used in the apparatus 1600.

Preferably, the locking system 1603 includes first and second lockingdevices 1604, 1605, FIGS. 36 and 39. Preferably, the first and secondlocking devices 1604, 1605 are constructed and arranged to interact witheach other. Preferably, the locking system 1600 includes a first, lockedorientation and a second, unlocked orientation. In the first, lockedorientation, the first and second locking devices 1604, 1605 interactwith each other. By the term “interact,” it is meant that the first andsecond locking devices 1604, 1605 engage each other sufficiently toprevent undesired movement of the V-pack filter 1500. In the second,unlocked orientation, the first and second locking devices 1604, 1605 donot interact.

In one example embodiment, the V-pack filter 1500 defines the firstlocking device 1604, FIG. 36, while the retention mechanism 1602includes the second locking device 1605, FIG. 39. Preferably, the firstlocking device 1604 includes at least a first interlocking member, orstructure, 1606 and the second locking device 1605 includes at least afirst interlocking member 1607. Preferably, the first locking member1604 is a female locking member 1608 and the second locking member is amale locking member 1610.

In the example embodiment illustrated in FIG. 36, the first framestructure 1510 defines the female locking member 1608. Preferably, thefirst end portion 1510 of the first frame structure 1510 defines alocking groove, cutout, notch, or receiver indent 1616. In the exampleembodiment illustrated in FIG. 39, the retention mechanism 1602 includesa control arm 1612. Preferably, the control arm 1612 includes the malelocking member 1610. Preferably, the male locking member is a lockingrib or projection 1614 extending from the control arm 1612. The lockingrib 1614 extends or projects outwardly from the control arm 1612 in thegeneral direction of the V-pack filter 1500 as illustrated in FIG. 39.Preferably, the locking groove 1616 of the V-pack filter 1500 isconstructed and arranged to receive the locking rib 1614 of theretention mechanism 1602. The locking rib 1614 fits within, engages, orinteracts with the locking groove 1616 of the V-pack filter 1500. By theterm “receive,” it is meant that the locking rib and groove 1614, 1616interengage with one another. By the term “interengage,” it is meantthat the interaction of the locking rib and groove 1614, 1616 issufficient to prevent undesired movement of the V-pack filter 1500during operation. In other words, the locking rib and groove 1614, 1616do not need to be frictionally engaged with one another but need onlyinteract sufficiently to prevent substantial undesired movement of theV-pack filter 1500.

When the V-pack filter 1500 is placed in the housing, such as thehousing 1 of FIG. 6, on the retention mechanism 1602, the retentionmechanism 1602 is used to move the filter V-pack 1500 into sealingengagement around the aperture and against the tube sheet. When theretention mechanism 1602 is placed in its raised, or locked,orientation, the locking rib 1614 of the retention mechanism 1602projects into the locking groove 1616 of the V-pack filter 1500. Assuch, the locking system 1603 centers the V-pack and stabilizes it fromundesirable misalignment.

Referring back to FIG. 40, it is noted that the first locking device1604 preferably also includes a second interlocking member 1617 having asecond locking groove 1618, opposite the first locking groove 1616. Eachlocking groove 1616, 1618 is being positioned at the ends 1579, 1580,respectively of the V-pack filter 1500. The second locking groove 1618is analogous to the first locking groove 1616. Preferably, the lockinggrooves 1616, 1618 are centered between the first and second panels1502, 1504 of the V-pack 1500. Preferably, in the particular embodimentillustrated in FIG. 40, the locking grooves 1616, 1618 are generallyU-shaped having two filets. The center of the semi-circle portion of theu-shape of the lock grooves 1616, 1618 is preferably located inboard ofthe ends 1579, 1580 of the V-pack 1500, at least 0.05 inches, preferablybetween 0.10 inches and 0.30 inches, and most preferably about 0.18inches. Alternatively, a variety of shapes and sizes could be utilizedfor the locking grooves 1616, 1618.

It is noted that the second locking groove 1618 of the firstinterlocking device 1604 might interact with a third interlocking device(not shown) on the housing.

Referring back to FIG. 39, preferably, the locking rib 1614 projectsfrom a front face 1681 of the control arm 1612 at least 0.05 inches andpreferably between 0.10 inches and 0.50 inches. Alternatively, a varietyof shapes and sizes could be utilized for the locking rib 1614.

During interlocking of the locking rib 1614 and the locking groove 1616,the locking rib 1614 extends generally into the locking groove 1616 atleast 0.05 inches and preferably between 0.10 inches and 0.50 inches.

Attention is now directed to FIG. 41. FIG. 41 is a perspective view ofanother embodiment of a V-pack filter 1700. Analogous to the V-packfilter 1500 of FIG. 36, the V-pack filter 1700 includes a frameconstruction 1703 and a first locking device 1704. The first lockingdevice 1704 includes a first interlocking member 1706 and an oppositesecond interlocking member (not shown). In this embodiment, the firstlocking device 1704 also includes a third interlocking member 1730.

The frame construction 1703 includes first and second frame structures1710, 1711, analogous to the frame construction 1506 of FIG. 36. Thesecond frame structure 1711 includes a top portion 1711 a. The topportion 1711 a includes a first side portion 1711 b, a second sideportion (not shown), a first end portion 1711 d, and a second endportion (not shown) extending therefrom. The first end portion 1711 ddefines the third interlocking member 1730. In particular, the thirdinterlocking member 1730 is a cutout, or notch 1731 in the first endportion 1711 d. Preferably in this embodiment, the first locking devicewould also include a fourth interlocking member (not shown) opposite andanalogous to the third interlocking member 1730 in the second endportion (not shown).

Although not shown, in this embodiment, a retention mechanism includes asecond interlocking device constructed and arranged to interact with thefirst interlocking device. In particular the locking rib, such as thelocking rib 1614 of the retention mechanism 1602 of FIG. 39, extends tothe top of the control arm, such as the control arm 1612 of FIG. 39.This locking rib engages with the first interlocking member 1706 and thethird interlocking member 1730.

It is noted that although not shown, the second and fourth interlockingmembers of the first interlocking device 1704 might interact with athird interlocking device (not shown) on the housing.

Attention is directed to FIG. 42. FIG. 42 is a perspective view ofanother embodiment of a V-pack filter 1800. Analogous to the V-packfilter 1500 of FIG. 36, the V-pack filter 1800 includes a first lockingdevice 1804. The first locking device 1804 includes a first interlockingmember 1806 and an opposite second interlocking member (not shown). Inthis particular embodiment, the first interlocking member 1806 is arecess, cutout, or indent 1808 in a side panel 1810 of the V-pack filter1800. Or, in other words, the side panel 1810 defines the indent 1808.

The first locking device 1804 is constructed and arranged to receive asecond interlocking device 1812. The second interlocking device includesa first interlocking member 1813. In this particular embodiment, thefirst interlocking member 1813 is a pin, or projection 1814. Theprojection 1814 might extend from a control arm of a retentionmechanism, such as the retention mechanism 1602 of FIG. 39. Theprojection 1814 might also extend from a door, such as the access door 5of FIG. 4. The first and second interlocking devices 1804, 1812 areconstructed and arranged to interact with each other.

Attention is directed to FIG. 43. FIG. 43 is a bottom elevational viewof another embodiment of a V-pack filter 1900. The V-pack filter 1900includes a first locking device 1904. The first locking device 1904includes a first interlocking member 1906. In this particularembodiment, the first interlocking member 1906 is a recess, cutout, orindent 1908 in a bottom frame section 1910 of the V-pack filter 1900.Or, in other words, the bottom frame section 1910 defines the indent1908.

The first locking device 1904 is constructed and arranged to receive asecond interlocking device (not shown). The second interlocking deviceincludes a first interlocking member (not shown). The first interlockingmember is a longitudinal projection, or bead, (not shown). Theprojection extends from the base structure of the retention mechanism,such as the retention mechanism 1602 of FIG. 39. The first and secondinterlocking device 1904 are constructed and arranged to interact witheach other.

1-20. (canceled)
 21. A filter comprising: (a) a frame constructionincluding a first frame structure and a second frame structure retaininga filtration media; (b) first and second panel sections mounted inextension between said first and second frame structures; (i) said firstpanel section having first and second ends, and said second panelsection having third and fourth ends; (A) said first and third endshaving a first distance therebetween; (B) said second and fourth endshaving a second distance therebetween, said second distance beinggreater than said first distance; (ii) said first and second panelsections and said second frame structure defining an air flow aperture;(c) a seal arrangement circumscribing said air flow aperture andprojecting outwardly from said second frame structure; and (d) a stoparrangement projecting outwardly from said second end.
 22. A filterassembly comprising: (a) a housing defining a first chamber and a secondchamber; (b) a first stage air cleaner positioned in the first chamber;(i) said first stage air cleaner including at least one filter accordingto claim 21 through which air to be filtered is directed during use; (c)a second stage air cleaner positioned in the second chamber; (i) thesecond stage air cleaner including at least one removable andreplaceable filter through which air is directed, during use; and (d) apulse jet cleaning arrangement constructed and arranged to selectivelydirect a pulse jet of air, in a reverse direction, through said at leastone filter during use.
 23. A method of operating an engine air intakefilter assembly having a pulse jet cleaning arrangement constructed andarranged to selectively direct pulses of air through an air filterarrangement, the method comprising: (a) measuring a pressure drop acrossthe air filter arrangement; (b) measuring an engine load during anengine operation; and (c) activating a pulse valve of the pulse jetcleaning arrangement to direct a pulse of air, in a reverse direction,through the air filter arrangement in response to the engine load beingbelow a predetermined engine load and the pressure drop exceeding apredetermined pressure drop.
 24. A system for operating an engine airintake filter assembly having a pulse jet cleaning arrangementconstructed and arranged to selectively direct pulses of air through anair filter arrangement, the system comprising: (a) a pressure dropcomponent that receives a measured pressure drop across the air filterarrangement; (b) an engine load component that receives a measuredengine load during an engine operation; and (c) a pulse firing componentthat activates a pulse valve of the pulse jet cleaning arrangement todirect a pulse of air, in a reverse direction, through the air filterarrangement in response to the engine load being below a predeterminedengine load and the pressure drop exceeding a predetermined pressuredrop.